Radio signaling system



May 20, 1930. A. G. CHAPMAN RADIO SIGNALING SYSTEM Filed NOV. 25, 1927 4: e -O l Itteawacar j, tomam- ATTORNEY Patented May 20, 1930 narran stares enterar@ cri-ice ARTHUR G. CHAPMAN, OF 'UPPER MONTCLAR, NEV JERSEY, ASSIGNOR 'IO AMERTCAN TELEPHONE .AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK RADIO SIGNALNG SYSTEM Appiicanon ined November as, 1927. serial No. 235,303. f

of two, parallel, like wave antennae separated by a fraction of a wave length and with one antenna displaced longitudinally a racticn r of a wave length with respect to the other,

has been called a staggered system. ,The antennae must be separated 1,000 to 1,200 feet apart to minimize crosstalk between them and each antenna requires a pole line for its support and a transmission line to bring the received currents to the radio receiver. Furthermore, the separation of the antennae produces a broadside effect, that is, the effect of space phase change from one antenna to 1 the other in undesired waves received from points not in line with the antennae in either direction, which etect mustbe Ataken into consideration. Y

My invention resides in a wave antenna system having the same directional characteristic as a particular form of the staggered system of the prior art would have/it the two antennae were placed on a single pole line, and if no cross-talk eects existed between them. My invention therefore requires only a single pole line, and no transmission lines for connection with the receiving station.`

This invention will be readily understood from the following description, when read in connection with the attached drawing, of which Figurel illustrates schematically the staggered wave antennae lot the prior art; Figs. 2 and 3 illustrate steps in the developmentA ot the invention; Fig. L illustrates schematically a simple form ot the invention;

. Fig. Lla shows a desirablemethodV for connecting the antenna conductors to the 'receiver; Fig. '5 showsthe `embodiment of the invention in a more practical form; and Fig. 5? is a detail of Fig. 5.

Fig. l shows schematically Athe particular staggered antenna system of the prior art to which my invention is equivalent in .directional characteristic. The antennaJ l and 2 are parallel and equal inlength, but shifted lengthwise a distance d1. This requires `a transmission line 3 to bring the current vl from the terminal C of antenna l to the radio receiver R at the right of the point D. A radio current z' is received at terminal G of antenna l and a current c"v is received at terminal D of antenna 2. These currents" are equal in magnitude but out of phase. The current i' leads the current z" by the phase angle o d1 cos 6 where o Z1 is the space phase change in length Z1 at any particular frequency and 6 is the angle of incidence for any particular radio signal (for the desired signal 6:0). The ctirrent 1i is retarded in phase by the angle gin being propagated from C to D and reduced by the attenuation factor ea. "The current z" is also attenuated by the atctor e'oill in passing through the attenuator' 4. Thus, there are two currents entering the receiver R of equal lmagnitude but one current leading by the angle (,Bodl cos 6 dl). The two currents combine to form the resultant current I which is about twice z' for 6:0, becomesa smaller part of c' as 6 increases and vanishes for aV value of 6 which makes the relative' angle equal to 180 degrees. Tn order to simplify the description of the principle'underlying this invention, the transmission line 3 is assumed to have the same phase change'd1 as the section CD of the wave antenna 2. lt is also assumed, or'tlie sake ot simplification, that the transmission line has the same attenuation factor e'Udl nsfthe wave antenna for the length d1. The actual attenuation factor ofthetransmissionline has no effect on the directional characteristic since the attenuation is compensated for. The transmission line would actually have less phase change Vthan cZl and if the arrangement of Fig. 1 were actually built an artificial line would be connectedin series `with 3 Vto increase'the phase change. The artiiicial line could be so adjusted to cause the total phase change between C and D to be dilerent .from

,Bell or the artificial line could be placed in series with antenna 2 but it is the staggered system having a phase change of ,Edi between C and D for antenna l to which my invention is equivalent in its directional characteristic. In Fig. l the overhanging portions AB and CD have the length d1, and the over lapping portion BC has the length d2. The total length of each antenna is indicated by (l. It is desirable to point out that throughout all of t-he figures the correspondingly designated sections have the same lengths as in Fig. l.

In Fig. 2 is illustrated a. staggered wave antenna system in which the separate antennae are divided into sections and the current set up in each section is brought to the common receiver R over separate transmission lines. Thus, the section AB ot antenna 1 is connected by the transmission line 5 with the receiver It, and the section BC of thatsame antenna is connected by the transmission linel 3 with the receiver. The section BC of antenna 2 is connected by the transmission line 6 with the receiver It, the connection including the attenuator 4. to which is also connected the section CD of antenna 2. In the arrangement shown in Fig. 2, the left-hand end of each part is assumed to be connected to ground through a. resistance that equals the characterisiic impedance of a wave antenna. The right-hand end of each section is connected to its transmission line through a transformer of suitable ratio to avoid reection effects at the junction ot the grounded and the metallic circuits. It the transmission lines have the same attennation and phase change as corresponding lengths of the wave antennae, it will be seen that the total received current at the point D is the same as in Fig. l, although at any other point upon the system the currents for either of the two antennae are not the same as in Fig. l. The attenuator 4 has the same attenuation factor as in Fig. l. The currents @"1 and '2 indicate the values which l and will have after propagation to the point D.

Fig. 3 shows a system in which the separate antennae of Fig. 2 have been replaced by a single antenna having the same directional characteristic as Figs. l and 2. It will be seen that the section BC of the antenna system of Fig. 2 supplies two components of the total current I at the point D of the system. One of these components is @"2, and the other is @"2 attenuated by the action of the attenuator 4, that is to say, '2 e-ail. The section BC of Fig. 3 supplies only one componentg and the total contribution of the section is reduced bythe ratio of l/ (l -le-a d1) or about one-half. This reduction is compensated :tor by similarly reducing the contributions ot' the other sections, namely, AB and CD, by means of the attenuators 7 and 8 inserted in the transmission lines of those sections. The result is that the total received current I1 of the arrangement shown in Fig. 3 is about one-half that ofthe arrangement ot Fig. 2, but the important thing is that the two currents have the same directional characteristic. The attenuator 8 not only accomplishes the reduction for the section CD but also performs the function of the attenuator 4 of the preceding figures. It is to be understood that the sections of the antenna of Fig. 3 have their left-hand ends terminated by resistance and their right-hand ends coupled with the transmission lines by suitable transformers. The arrangement shown in Fig. 3 requires only a single pole line for the support of the antenna system, but it is apparent that the transmission lines extending from the right-hand ends of the sections must he supported and therefore the system as thus disclosed, is not an improvement over the multi-antennae systems of the prior art, such as shown in Fig. l. The transmission lines 3 and 5 ot Fig. 3 could not practically be carried upon the same pole line as the. antenna because a circuit composed of the two wires of a transmission line with ground return would pick up radio signals an-d these would induce unwanted radio signals in the paralleling wave antenna. This diiiiculty, however, is overcome by the arrangements shown in Figs. 4 and 5.

In Fig. 4 is disclosed a two-wire system in which the two wires act in parallel to ground as an antenna and, at the same time, serve as a metallic circuit for the transmission of the antenna currents from the various sections to the receiver It. The current il, which is set up in the section AB comprising the two wires in parallel to ground, is transmitted through the attenuator 7 and is propagated over the section BC to the point C where it combines with the current 7'@ which has been set up in the section BC. The resulting current, flowing to ground through the transformer T1, is transmitted over the section CD metallically, and is, in turn, impressed by the transformer T2 upon that branch of the receiving circuit which includes the artificial line ALl. This artiicial line compensates for the difference in the phase change between the metallic circuit andthe ground circuit for the section CD which in length equals (Z1. The metallic circuit CD and the artificial line AL1 provide the same total phase change as the line 3 of Fig. 3. At the point F is a coupling' net work similar to a four-wire terminating set for the purpose of coupling the various circuits with the common receiver without producing interaction between the various circuits. Fig. 4a shows a schematic wiring diagram of a 4- wire terminating set. The section CD serves asa grounded circuit to intercept the radio signals, the currents of which flow through a winding oi the transformer T3. This current 3 is impressed by the transformer T3 upon this. the antenna metallic circuit CD and for the artificial line AL1 at E. The factors for attenuators 7 and 5 of Fig. l involve all, that is, the staggering distance, and a the attenuation constant of the two-wire ground returnV circuit. This arises from the fact that the system shown in Fig. 1' requires that equal currents propagated from the point C to the receiver R over the two paths differ after reaching R by the attenuation factor of the groundreturn circuit CD. For the sake of simplicity it has been assumed that the transformers T1, T2, and T3 are perfect, but actually such transformers will introduce undesired phase and magnitude differences in the currents delivered to the combining network at the point F, and such dierences will have to be corrected by suitable modification of the networks AL;L and 5. It may be stated that practically the network at E would be an adjustable articial line of low attenuation and that at 5 would be an adjustable attenuator and artificial line providing separate adjustments for phase and magnitude. Bymeans of such adjustments, the directional ldiagram of the system shown in Fig. l may be varied to give the best result for a particular location.

The practical arrangement of the invention is shown in schematic form in Fig. 5. As is well known, it is customary in wave antenna systems to have the receiver at that end of the wave antenna which is nearer the transmitting station. This is accomplished by transmitting the signal current back from the more distant end of the antenna to the said end that is nearer the transmitter. The same idea has been incorporated in the arrangement shown in Fig. 5 in which the direction of transmission of the wave in space is from left to right. Tn order to Vaccomplish l comprises a four-wire line. The four wires in parallel to ground serve as interceptors of radiant energy, and at the same time the two pairs of conductors as metallic circuits serve for the propagation of the currents back from the distant end to the end at which the receiver is located. The four wires in parallel to ground between the points A and B serve to intercept the signals, the

currents of which are attenuated by the networks shown at the point B. The currents, as thus attenuated, combine with the currents set up in the section BC acting as an antenna to intercept the space wave. The combined currents flow to ground through the winding 9 of the transformer T4. This current therefore produces avoltage across the winding 10 of this same transformer and the current is propagated over the metallic circuit 2 to the receiver It nectionA including the transformer T5, the network G and the combining network F. The current that is produced by the radiant energy in the section CD, comprising the four conductors in parallel to ground, flows to ground through the winding 11 of transformer TG. This current creates a voltage across the winding 12 of the same transformer, and the resultant current is transmitted through the transformer T7 to the metallic circuit 1 and thence through the transformer Ts to the receiver 8, the connection including the attenuator 0 and the network F. The phase-changing network Gr compensates for the fact that the current, produced in the section AC by the interception of radiant energy, does not have to traverse the section CD before it is transmitted to the receiver B. This will be apparent when it is realized that the current resulting from antenergy by the section CD, when reflected by the transformer T6, must traverse not only the metallic circuit 1, which equals in length the metallic circuit 2, but also must traverse the metallic circuit 3. The attenuation factor of the network Gis e1'1.e'md1. The subscripts m and g referto the two-wire metallic and four-wire-grounded circuitsrespec tively. The attenuator 6 performs the same function as attenuator 5 attenuation factor of 6 should be where k1 compensates for the attenuation at the left-hand end, the conc the interception of the radi- 2.

in Fig. 4l. The :1'

factor of the network G. The factor eoml j in the denominator compensates for the extra attenuation of the current from the antenna section CD in the metallic circuit 3. rlhe other factor in the denominator occurs for the same reason that 1 -l-eddl occurs in the denominator of the attenuation factors of attenuators 8 and 5'..V The attenuators at B in Fig. 5 perform theV Vsame function as attenuator 7 in Fig. 4, that is, they reduce the current from the four-wire antenna section AB by the factor l/ (1-l-e0d1). The attenuator andthe phase-changing network at the receiver should be adjustable.

The attenuation networkatB in the four.-

wire circuit of Fig. 5 consists of five resistlances designated a, Z2, 79, a, and c. For practical conveniencev a should equal 600 ohms, Z9 1200 ohms, and c 117 0 ohms, approximately. With those constants, the loss introduced in each metallic circuit is Vabout 10 TU. The large losses in the metallic circuits may be avoided by a transformer arrangement having a T-network, as shown in Fig. 5a. Such an arrangement might tend to introduce unllO desired phase changes in the four-Wire antenna circuit, due to the inductance of the transformer windings, but such could probably be corrected by special transformer delsign.

The arrangements shown in F l and 5 disclose schematically a directional receiving system involving a single Wave antenna having the directional characteristics of a staggered Wave antenna system and in which the separate antenna sections serve not only to intercept radiant energy but also to transmit metallically to the radio receiver the currents set up in the precedingl antenna sections. Since the arrangements disclosed require only a single pole line, they are much more economical in construction than those of the prior art. They furthermore do not require separate pole lines for the transmission cir cuits, and therefore, avoid the defect in the system shown in Fig. 3.

lVhile the invention has been disclosed as embodied in particular forms, it is to be understood, of course, that those forms are merely illustrative of the invention. The invention is not to be construed as thus limited, but has the scope of the appended claims.

What is claimed is:

l. In a Wave antenna system for directional,

signaling the combination with a Wave antenna comprising a plurality of sections, of means to render certain sections interceptors of radiant energy and as transmission lines for the currents produced in other sections by intercepted energy, a terminal circuit including means to vary the phase and the attenuation of currents in certain sections, means to combine the currents as thus varied and means to receive the combined currents.

2. In a Wave antenna system for directional signaling the combination with a Wave antenna comprising a plurality of sections each consisting of tivo pairs of conductors effectively connected in parallel to ground to constitute an interceptor of radiant energy, of means for impressing upon one of said pairs the voltage resulting from the combined current of all of said parallel conductors constituting one section of said antenna, means to impress upon the other of said pairs a voltage resulting from the combined current of all of the parallel conductors constituting another section of said antenna, and a terminal circuit having means to variably control either the phase or magnitude or both of the said currents impressed thereon by the said pairs of conductors, means to combine the said currents, and a receiving device upon which the combined currents are impressed.

3. In anantenna system for signaling in a predetermined direction, the combination With an antenna made up of a plurality of sections, each of which serves as an interceptor of radiant energy and as a conductor for the transmission of currents resulting therefrom, of connecting means between the adjacent sections to impress upon each subsequent section the currents flowing in the preceding section for transmission thereover, and means to receive the combined currents.

t. In an antenna system for signaling in a predetermined direction, the combination With an `antenna made up of a plurality of sections, each of Which consists of a pair of conductors, of means to couple the said pairs of adjacent sections so as to constitute a plurality of coupled metallic circuits for the transmission of currents, the said coupling means being so connected to ground that the Wires of each section serve in parallel as intercept-ors of radiant energy.

5. In a Wave antenna system for directional signaling the combination with an antenna comprising a plurality of sections Whose longitudinal axes lie approximately in the same straight line, of means connected With the sections of the said antenna to render each section a collector of radiant energy and to join the adjacent sections so that each acts as a` transmission line for the conveyance of currents resulting from the energy collected by the preceding one, and a receiving device upon which the currents of all sections are combinedly impressed.

G. In a Wave antenna system for directional signaling the combination with a Wave antenna comprising a plurality of sections each consisting of two pairs of conductors effectively connected in parallel to ground to constitute a collector of radiant energy, of means for impressing upon one of said pairs the voltage resulting from the combined current of all of said parallel conductors constituting one section of said antenna, means to impress upon the other of said pairs a voltage resulting from the combined current of all of the parallel conductors constituting another section .of tlm said antenna, and a terminal circuit upon Which are impressed the currents transmitted over both pairs of conductors.

In testimony whereof, I have signed my name to this specification this 21st day of November, 1927.

ARTHUR Gr. CHAPMAN. 

